This invention relates to a process for preventing growth of marine organisms on the surface of apparatus and/or pipe constituting flow path for sea water and plant utilizing sea water.
Industrial utilization of sea water has increased considerably. For example, much sea water is being used in steam power plants, iron-making works and in the petrochemical industry. Sea water is also being used for cooling ship condensers. Trouble caused by marine organisms, such as shellfish (mussels, barnacles, etc.), Polyzoa and Hydrozoa can not be disregarded. When such marine organisms adhere to the surface of pipe and/or plant constituting a flow path and grow thereon, the flow path of the pipe and/or plant becomes narrower. When many marine organisms adhere to the surface, some come off the surface and enter the condenser of the boiler and heat exchanger, thereby lowering the cooling efficiency thereof. Clogging of condenser tubes by particles from the surface gives rise to turbulent flow of the sea water, and the flow accelerates corrosion of metal.
A chlorine-generating agent, an organic tin compound, an organic sulfur compound, and a quaternary ammonium salt have been used in order to prevent such trouble. However, such agents have residual toxicity and accumulate in sea water. It is believed that large accumulations of such agents break the ecological system of the sea. For example, in order to prevent growth of marine organisms on a surface by adding chlorine and/or a chlorine generating agent to sea water, the agent must be used so as to provide concentration of resident chlorine and/or hypochlorite in sea water in the range of 0.1-0.2 ppm. Therefore, 1-2 ppm of available chlorine must be continuously added to the sea water in contact with the surface. Similarly, in case of using an organic tin compound, the compound must be continuously or intermittently added to the sea water so as to provide a concentration of the resident compound in the sea water in the range of 0.005-0.5 ppm. In case of using an organic sulfur compound, the compound must be continuously or intermittently added to the sea water so as to provide a concentration of the resident compound in sea water in the range of 1-10 ppm. In addition, when using chlorine, transportation of chlorine is dangerous and it is difficult to safely supply chlorine to the sea water.
Therefore, development of an agent to substitute for the chlorine-generating agents, the organic tin compounds, the organic sulfur compound or the quaternary ammonium salts, has long been desired, and research for reducing the amount of these agents when they are employed has been carried out.